The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No.198 42 188.5, filed on Sep. 15, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention concerns a reel winding device having a winding bed with two support rolls that form side walls of a pressure chamber which is also bounded by a bottom wall.
2. Discussion of Background Information
In one of the final production steps, paper webs are usually cut to the proper width and then wound into reels before being packaged and delivered. In contrast to the drums used during paper production, the winding cores onto which the paper reels are wound have only relatively slight rigidity and load-bearing capacity. They are often constructed, e.g., as cardboard tubes. This leads to the paper reels usually being supported during winding by supporting rolls. This occurs particularly when the winding device is structured as a support roll winding machine. Here, the reel lies on support rolls without additional holding forces gripping the core. But even with a support roll winder, in which additional holding elements grip the reel core, the reel is supported on a roll. When the paper reels become larger and heavier, the linear support forces of the paper reel become relatively large on the support roll or rolls, which has the disadvantage of increasing the winding tightness. This can lead to a subsequent failure in the winding structure of the roll. To relieve the pressure on the reels and to reduce the linear force, a pneumatic overpressure can be generated under the reel so that at least part of the reel weight is supported by an air cushion.
The air cushion is generated in the pressure chamber. The pressure chamber is bounded on the left and on the right by the two support rolls, by the winding reel on the top, and by the bottom wall on the bottom. Additional sealing measures, which are, however, of secondary importance for the present invention, are provided for the ends. During operation, the bottom wall should move as close as possible to the support rolls. If the material web enters the winding bed from below, it is not desirable for the bottom wall to touch the material web. However, a sliding contact with the other support roll which is not surrounded by the material web may be permitted if the surface of the bottom wall is appropriately structured. In most cases, however, a small gap is permitted with two support rolls.
However, the requirement that the bottom wall be as close as possible to the support rolls makes handling of the reel winding device more difficult when a new material web is to be introduced into the winding bed. This is nonetheless essential from time to time, for example, after a web break. The threading of the material web into the narrow gap between the corresponding support roll and the bottom wall takes a relatively long time. In the event of a web break, a paper jam, which can only be removed with great effort, may occur in the pressure chamber. In the worst case, it can even cause destruction of the seals or of the support roll.
DE 195 24 905 A1 proposes placing the bottom wall, which is structured as a sealed box, on a movable carrier. In other words, the bottom wall is completely pivotable from its operating position into a resting position.
However, this procedure requires a significant design outlay. Normally, the bottom wall must cover the entire axial length of the winding device. This is usually the working width of an upstream paper machine and may be as much as 10 meters. This design makes it difficult to maintain a constant sealing gap between the support rolls and the bottom wall. The application and retraction of the bottom is relatively expensive since large masses must be moved.
The present invention provides for a reel winding device which includes a winding bed composed of two support rolls that form side walls of a pressure chamber, and a bottom wall having at least one movable sealing body disposed between the bottom wall and at least one support roll. In the device, at least one movable sealing body is adapted to move in a direction away from the winding bed and may be loaded with a positioning force, such as a force spring, in the direction of a sealing position or may be loaded with a path-length independent force from a positioning motor. The positioning force may be substantially in equilibrium with the sum of the weight of the sealing body and a force resulting from a compressed air load. The at least one movable sealing body may work in cooperation with a stop motion device and/or with a position sensor, which emits an error signal in the event of a displacement of the sealing body away from the support roll.
In another embodiment, the at least one movable sealing body contacting the support roll may be a sealing edge, which may also be movable along a plane which is sloped relative to a perpendicular mid-plane through the winding bed. The bottom wall of the device may be sloped in the direction toward the sealing body. The device may further include a stationary seal disposed between the bottom wall and one support roll, such that the direction of rotation of the one support roll runs from the bottom wall to the winding bed.
The present invention provides for a process for supporting a winding reel on an apparatus that includes a winding bed formed by two support rolls that form side walls of a pressure chamber, and a bottom wall having at least one movable sealing body disposed between the bottom wall and at least one support roll, the process including: rotating the winding reel, rotating the support rolls, and positioning the at least one movable sealing body in a vicinity of a circumferential surface of at least one support roll. The process further includes moving the at least one sealing body in a direction away from the winding bed. The process further includes loading the at least one movable sealing body with a positioning force, such as a spring force, in the direction of a sealing position or loading the at least one movable sealing body with a path-length independent force from a positioning motor. The positioning force may be substantially in equilibrium with the sum of the weight of the sealing body and a force resulting from a compressed air load. The at least one movable sealing body may cooperate with a stop motion device and/or with a position sensor, which emits an error signal in the event of a displacement of the sealing body away from the support roll.
In another embodiment, the at least one movable sealing body contacting the support roll may be a sealing edge, which may also move along a plane which is sloped relative to a perpendicular mid-plane through the winding bed. The bottom wall may be sloped in the direction toward the sealing edge. The process further includes disposing a stationary seal between the bottom wall and one support roll, such that the direction of rotation of the one support roll runs from the bottom wall to the winding bed.
The present invention is also concerned with simplifying handling in the zone of the seal, particularly in a reel winding device of this invention where a movable sealing body is disposed between the bottom wall and at least one support roll.
This has several advantages. The bottom wall can be structured as a xe2x80x9cblow boxxe2x80x9d, i.e., a body with a certain extension into the chamber, and can be disposed rigidly, i.e., immovable relative to the support rolls. Thus, the necessity of moving relatively large masses is avoided. The bottom wall can be positioned with relatively high precision relative to the support rolls. This position can be maintained during operation without the necessity of a complex structure. In addition, the shape of the bottom wall or of the blow box can also remain unchanged. For example, a normal rectangular profile with its shape-related stability is possible. Changes in the geometry are effected only by the sealing body or bodies. The sealing body is a separate component which can be inserted into the intermediate space between the support roll and the box with the bottom wall. The sealing body is a relatively lightweight component compared to the bottom wall. Since the box of the bottom wall can support the sealing body over the axial length of the support roll, i.e., parallel to the axis of rotation of the support roll, the sealing body need not have very great intrinsic stability. If an additional gap develops that needs to be sealed, i.e., a gap between the bottom wall and the sealing body, the air loss which can occur through the gap is offset by the advantages of the movable seal on the rigid and stationary bottom wall.
Advantageously, the sealing body is moveable away from the winding bed in one direction. Above all, this embodiment has an advantage if the material web breaks, as it often happens. If the material web breaks in the zone between the two support rolls, the material web is advanced into the winding bed without being picked up by the winding reel. A paper clog then develops, and it may result in damage to the support rolls and/or the bottom wall. But since the sealing body is moveable away from the winding bed, the sealing body moves away, thus permitting the paper web to escape from the zone between the support rolls.
Preferably, the sealing body is positioned with a positioning force in the direction of a sealing position. Thus, the sealing body is not rigidly or immovably fixed on the bottom wall, but rather is held in the desired position by a positioning force. If a force acts in the opposite direction such as that caused by incoming paper in the event of a malfunction, the sealing body is automatically pushed away and lets the paper clog pass through. The danger of damage is kept low.
It is also preferable that the positioning force be substantially in equilibrium with the sum of the weight of the sealing body and a force resulting from a compressed air load. The positioning force may in some instances be somewhat greater. When equilibrium exists, a small force is adequate to move the sealing body away from the support roll. Such a small force may arise if a malfunction occurs, thereby obviating the development of a greater problem. Even the threading of a product web is simpler if the web is introduced from below between the support rolls, since smaller forces are required to move the sealing body away from the support roll to provide the necessary manipulation space.
Preferably, the sealing body is spring-loaded. The spring thus presses the sealing body into its sealing position. This is a very simple and virtually maintenance-free embodiment.
In an alternative embodiment, the sealing body is loaded by a positioning motor with a force independent of the length of the path. The positioning motor can operate pneumatically, hydraulically, electrically, or magnetically. With this design, the force necessary to move the sealing body from the support roll does not increase with the increase in distance. Thus, the sealing body can free the entire opening when a malfunction occurs and before great counterforces develop.
In a preferred embodiment, provision is made for the sealing body to work in cooperation with a stop motion device. The stop motion device may be positioned, for example, on the bottom wall. With this design, it is possible for the sealing body to seal without contacting the support roll. The movement of the sealing body is limited in each case by a stop.
In an alternative embodiment, provision can be made for the sealing body to contact the support roll with a sealing edge. In this case, there is a contact seal. The thrust or the motion of the sealing body is not restricted until it contacts the support roll.
Preferably, the sealing body works in cooperation with a position sensor which emits an error signal if the sealing body is displaced from the support roll. The sensor can be structured as a movement or proximity switch. Thus, a controlled stopping of the winding device or even intentional cutting of the material web is possible. Until now, it was not precisely known when a paperjam was occurring between the support rolls, because the web tension measurement systems customarily used cannot detect a paper break. Thus, after a tension interruption is caused by the support roll and paper reel, the paper is further advanced. Now, if a paper jam occurs, the sealing body is shifted to the right or to the left by the bottom wall because of the accumulation of paper (or some other material web), and the winding device is capable of being stopped for safety reasons. Moreover, this has the advantage that further amassing of paper in the winding bed can be avoided.
In a preferred embodiment, the sealing body is movable along a plane which is sloped relative to a perpendicular mid-plane through the winding bed. In this case, the sealing body can be moved below the bottom wall in its movement such that the opening or gap freed becomes even larger. Thus, the risk of a paper or material web jam occurring decreases even further.
Here, it is preferable for the bottom wall to be sloped in the direction of the sealing body. If the bottom boundary wall of the pressure chamber has a slope and paper is collected in the pressure chamber, the xe2x80x9cclogxe2x80x9d will slide under the effect of gravity on the angled bottom plate in the direction of the sealing body. This movement usually occurs before any movement which is caused by the pressure of the collected paper. In the case of failure, the paper web will thus be able to move out of the pressure chamber at an earlier time.
It is also advantageous for a stationary seal to be arranged between the bottom wall and one support roll, such that the rotational direction of this support roll runs from the bottom wall to the winding bed. The possibility that a material web may jam between the stationary seal or sealing arrangement and the support roll is relatively low. As soon as a material web introduced into the pressure chamber comes into contact with the appropriate support roll, the web is again moved away from the seal due to friction between the material web and the support roll. The other support roll, which rotates such that its surface moves toward the moving sealing body, is more critical. If a material web or a material web clog is impelled by this support roll, the clog is capable of pushing the sealing body away such that the material will not collect in the pressure box.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.